Compare Arteries, Veins and Capillaries in Terms of Their Features and Functions.

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|Biology: |Chapter 12 Transport of substances in humans | |Combined Science: |Chapter 10 Transport of substances in humans |

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*Write an essay on the following topic.
Compare arteries, veins and capillaries in terms of their features and functions.(12 marks) ##
Content (maximum 9 marks)
|Contents |Differences |Marks | |Features |Arteries have thicker wall to withstand the high blood pressure | | | |Veins have thinner wall. | | | |Capillaries have the thinnest, one cell thick wall which shortens the diffusion distance for | | | |the exchange of materials. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |(max. 4 marks) | | |Arteries possess no valves except at the base of the pulmonary artery and aorta inside the | | | |heart to prevent the backflow of blood. | | | |Veins possess valves at intervals to prevent the backflow of blood. | | | |Capillaries have no valves. | | | |Arteries have smaller lumen. | | | |Veins have larger lumen to reduce the resistance of blood flow. | | | |Capillaries have the smallest lumen which is about the same diameter as a red blood cell to | | | |increase the surface area for diffusion. | | |Functions |Arteries carry blood away from the heart | | | |Veins return blood towards the heart | | | |Capillaries carry blood from arteries to veins in the tissues. | | | | | | | | | | | | | | |...
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